Stabilizer for centrifugals operated with a liquid charge



2 Sheets-Shee 1 May 3, 1955 J. igERTRICH STABILIZER F R CENTRIFUGALSOPERATED WITH A LIQUID CHARGE Flled April 30, 1949 IN VEN TOR. (1451521/7KIfiI6/l J. HERTRICH May 3, 1955 m w E P 0 ma A G m m RC D m1 cm I R LA R E w I B A T s 2 Sheets-Sheet 2 Flled April 50, 1949 Hill I N V ENTOR. lager/1 fiEKTK/fi mf 4270405 .r

United States Patent 0 STABILIZER FOR CENTRIFUGALS OPERATED WITH ALIQUID CHARGE Joseph Hertrich, Hamilton, Ohio, assignor to The WesternStates Machine Company, Hamilton, Ohio, a corporation of UtahApplication April 30, 1949, Serial No. 90,622

9 Claims. (Cl. 210-63) machine can be safely operated with a body ofliquid in 1.

its spinning basket.

The invention is applicable to centrifugals having baskets of either thesolid bowl or the perforated wall type, in which the charge processedcomprises at least an inner layer of liquid. The charge material treatedin such centrifugals is usually a liquid or sludge from which eitherliquid and suspended solid components or different liquid components areseparated by centrifugal force.

It is well known that the effectiveness of centrifugal separation varieswith the speed and the radius of rotation of the charge in thecentrifugal basket, which determine the centrifugal force applied. It isalso well known that the speed attainable safely in practical operationsusing a large basket is far more limited in processing a liquid orsludge that forms a body of liquid in the basket than it is inprocessing charge material that forms a solid or non-flowing body in therotating basket. In the former case the annular layer or wall of liquidin the basket becomes uneven under certain critical speed conditions,and when the basket is operated on a solidly mounted shaft the resultingunevenness of weight distribution produces intensive vibrations thatbecome intolerable beyond certain limiting speeds of rotation. When thebasket is mounted on a gyratory shaft the resulting eccentricity ofweight causes the basket to gyrate dangerously and even to strikeagainst its surrounding casing or curb under certain conditions.

Accordingly, centrifugal separations requiring the presence of arotating annular body of liquid in a large spinning basket have beenlimited in effectiveness heretofore by the instability of thecentrifugal operation with a liquid charge. This instability has imposedsevere limitations upon the speeds of rotation safely to be reached,

and by thus limiting the available centrifugal force it has keptcentrifugal separation inapplicable, as a commercially practical matter,to various liquid charge materials that otherwise might be processed toadvantage in centrifugal machines.

The principal object of the present invention is to pro- Patented May 3,1955 that excessive vibrations or gyrations produced in operating acentrifugal basket at a high speed with an annular body of liquid in thebasket can be prevented, or can be overcome after having commenced, byimposing a drag or obstruction upon fluid rotating with the spinningbasket adjacent the inner face of the charge therein so as to retard therotation of the fluid in a portion of its orbit. For this purpose a dragmember may be held in the path of the rotating fluid, for example, amember presenting stationary surfaces in said path which lie in planestransverse to the axis of the charge rotation and are spaced apart inthe direction of that axis over a large part of the height of thecharge.

The drag member preferably is made with a plurality of vertically spacedbaflles or blades having edges disposed horizontally or at a small angleto horizontal and movable to insert these edges into the surface of theliquid of the spinning charge without objectionable disturbance of theliquid.

While the greatest stabilizing effect may be obtained by thus engagingthe drag member with the liquid of the charge, it has been found that adegree of stabilization effective to prevent undue swaying of the basketunder many circumstances can be obtained by merely holding the dragmember close to the charge liquid across the path of the strong aircurrents which circulate there as the basket spins at high speed. Ineither case, the edge of each blade imposes a drag upon the surface ofthe spinning liquid along an are lying transverse to the axis of thecharge rotation.

A stabilizer quite effective for the purposes of this invention may beprovided as a group of vertically spaced blades held inside the spinningbasket, lying transverse to its axis of rotation, and movablehorizontally to from the surface of a liquid charge in the basket.Whenever excessive vibrations or gyrations occur in the centrifugaloperation at high speeds, or during stages of such operation when theywould otherwise occur, the group of blades may be moved bodily towardthe surface of the liquid, either to approach it closely or actually toimmerse the blade edges in the liquid surface, thereby imposing a dragon a spinning fluid component of the system which retards its rotationin the zone of the stabilizer with consequent avoidance or prevention ofbasket instability.

A further feature of this invention arises from the discovery that theefficiency of the centrifugal separation as well as the stability of thecentrifugal operation may be influenced favorably by imparting a certaindirectional flow to the inner surface of the rotating body of liquid inthe centrifugal basket, particularly in counteraction to a flowgenerally induced on the same surface from the introduction of liquidcharge material at one end portion of the spinning basket. Thisdirectional force may be applied to the surface of the rotating liquidby a slight inclination of stabilizing projections or blades acrosspaths of rotation of the liquid. For example, in operating with avertical centrifugal basket to which liquid charge material isintroduced at the bottom, the liquid added to the spinning chargegenerally runs up the liquid inner surface of the charge, but byinserting. stabilizing blades into the liquid surface at a slightdownward inclination this action may be avoided so as to bring about amore eflicient centrifugal separation or settling of solids, apparentlythrough more even distribution of the added material into the charge.

Other objects, features and advantages of this invention will becomeapparent from the following detailed description of an illustrativeembodiment and from the accompanying drawings in exemplificationthereof, wherein:

Fig. 1 is a plan view of portions of a centrifugal ma- 3 chine embodyinga liquid stabilizer in assembly with other elements according to thisinvention;

Fig. 2 is a perspective view of the liquid stabilizer;

Fig. 3 is a vertical section taken approximately along line 33 of Fig.1; and

Fig. 4 is a fragmentary vertical section taken approximately along line44 of Fig. 1.

According to the illustrated embodiment, the invention is applied to acentrifugal machine employing a large open-top vertical basket 1 whichis carried by a vertical shaft 2 suspended from an overhead gyratorycentrifugal head or mounting (not shown) of any suitable or knownconstruction. The basket is enclosed within a surrounding stationarycasing or curb 3 in well known manner, so that liquid filtered throughor overflowing the basket is collected by the casing. The basket may beone of the solid wall or bowl type, in which case the cylindrical sidewall 4 is imperforate; or wall 4 may be a perforated wall whenseparating fine particles of solids from a sludge or slurry, if it ispre-lined by solids to form a filtering medium suitable for retainingthe fine particles.

The side wall 4 is held between the basket bottom 5 and the open baskettop 6 so as to define an inwardly opening annular space 7 in which acharge is held and subjected to centrifugal separation at high speeds ofrotation in the operation of the machine. As is well understood in theart, this space may be either uninterrupted as here shown or dividedinto separate annular channels by vertically spaced horizontal partitionrings, the latter arrangement being commonly used in known practiceswhere a liquid or sludge constitutes the charge material in process.

As seen in Figs. 1 and 3, the casing 3 has a top 3a which extendsinwardly to overlie the inner edge of the basket top 6. A portion 31) ofthis casing top may be utilized for mounting the liquid stabilizer andother parts, although various other supporting structures may serve aswell. A feed tube 10 extends vertically through por tion 312 to alocation inside the basket where the tube end 11 delivers liquid chargematerial introduced through the tube to the bottom of the basket. Thefeed tube is mounted on the casing top by means of a hub 12, withrespect to which the tube is turnable about its axis for the purposehereinafter described.

It will be evident that when a liquid charge material is suppliedthrough tube 10 and the basket 1 is in rotation, the material is walledup by centrifugal force as an annular charge 14 (Fig. 4) in the space 7(Fig. 3). This charge comprises at least an inner layer of liquid havinga liquid inner surface 15, while suspended solids or other components ofgreater specific gravity in the charge material may build up as a layerat the inside of the basket wall 4. The liquid at 15 forms a freesurface of revolution which has a paraboloidal form.

The removal of liquid from the basket 1 may be accomplishcd byoverflowing liquid from the basket, for example, over the rim 6a of thebasket top 6 into the surrounding casing 3, or by gradual filtration ofthe liquid layer through accumulated solids and a filtering medium nextto wall 4 when this wall is perforated, or to any desired extent by theaction of a scoop element 16. This scoop element comprises a curved tube17 held inside the basket by a bracket 18a on a vertical stub shaft 18,and having a mouth 1 disposed away from the charge surface 15 in oneposition of shaft 13 but movable into that surface in another positionso as to scoop liquid from the surface. The curve of the scoop tubeleads it to a discharge end 20 which lies above rim 6a in space betweenthe basket top 6 and the casing top 30, so that liquid scooped into thetube at 19 from the rotating liquid surface is discharged over the topof the basket into the casing. The scoop shaft 18 is supported turnablyin a hub 21 above casing top portion 312, hub 21 in turn being held, forexample, by a strap 22 fixed to the feed tube hub 12.

Referring now more particularly to the manner of stabilizing thecentrifugal operation, a stabilizer is pro vided which comprises aplurality of blades 31 lying transverse to and spaced apart along theaxis of rotation of the basket, and movable horizontally as a unitarygroup toward and away from the liquid surface 15, with their free edges32 nearly parallel to lines of rotation of air currents and liquid atthe surface of the charge. The blades 31 may be held as a unitary groupby welding or otherwise mounting them upon a base 33 which extendsvertically in spaced relation to the basket shaft 2 and which may besecured to a vertical support in the form of a sleeve 34 extendingdownward into the basket on the turnable feed tube 10. The sleeve 34 isfitted to turn with the feed tube 10. Hence it is evident that uponcounterclockwise movement of tube 10 about its axis from the positionshown in Figs. 1 and 4, the stabilizer 30 is moved closer to the chargeor even to a position Where the blade edges 32 will enter the spinningliquid surface 15.

According to a further feature of this invention, as seen in Figs. 3 and4, the blades 31 preferably slope laterally from the tube support 10' ata slight pitch or downward inclination from horizontal, so that inentering the spinning liquid in the basket they will impart a generaldownward flow to the surface of the liquid charge. A downward pitch ofonly about inch in 6 inches of blade length is satisfactory, and thepitch should be slight in order to avoid too much disturbance of theliquid surface. The downward fiow thus imparted to this surfacecounteracts the tendency of liquid introduced from end 11 of the feedtube to run up the same surface, and thus a better distribution of addedcharge material and a better centrifugal separation are obtained.

As illustrated in Figs. 1 and 3, further provisions are made forconvenient movements of the stabilizer 30 and the scoop element 16 toand from their respective active and inactive positions under manualcontrol by an attendant of the centrifugal machine. For this purpose anoperating mechanism indicated generally at is connected with theturnable stabilizer support or feed tube 10 and extends to an operatingposition outside and at the front of the casing 3, where this mechanismmay be moved by an attendant watching the stabilizer and the surface ofthe rotating liquid in the basket 1; and a similar operating mechanismindicated generally at is connected with the scoop element support orstub shaft 18 and extends similarly to the same operating position,where an attendant manipulating the scoop element can watch its actionupon the liquid content of the spinning basket.

The stabilizer operating mechanism 40, in the form shown, includes anarm 41 secured to and extending radially from the turnable feed tube 10atop its hub 12, a connecting rod 42 articulated at one end to the endof arm 41, and a long lever 43 mounted to turn on a fixed fulcrum 44.Lever 43 has a backward extension 45 articulated to the other end ofconnecting rod 42 and a forward extension terminating in a handle 46 atthe front of the machine. The scoop operating mechanism comprises,similarly, an arm 51 fixed to and extending radially from the top of thestub shaft 18, a connecting rod 52 articulated to the end of this arm,and a long lever 53 mounted on fulcrum 44 below lever 43 with a backwardextension 55 articulated to rod 52 and a forward extension terminatingin handle 56 at the attendant's station.

In the full line positions of the operating mechanisms as seen in Fig.1, where lever 53 lies directly below lever 43, the stabilizer 40 andthe scoop element 16 are both disposed away from the rotating liquidsurface in the basket 1 substantially as they appear in Fig. 4. Thestabilizer element is inserted into the liquid surface when handle 46 oflever 43 is moved to its broken line position in Fig. 1, and the scoopelement is activated when the attendant moves handle 56 of lever 53 toits broken line position in the same figure.

The operation of the present invention will be apparent from theforegoing description, but a further understanding of its importance andits effects may be gained from examples of practical application of theinvention.

One of these involves its use substantially as here described for theseparation and drying of precipitated calcium carbonate of extremelyfine particle sizes from a liquid slurry in which the particles areformed. In this practice the basket wall 4 may be a perforated walllined with a very fine filtering medium, such as paper pulp, and thebasket may be one of large diameter, say 40 inches, suspended from agyratory mounting or head in known manner and adapted for operation tohigh speeds in the range of about 1700 to 2200 R. P. M. The basket maybe rotated at less than its full speed while the slurry is introduced soas to form an annular precoating or layer of calcium carbonate insidethe basket wall by filtration of the slurry liquid, and then it may bebrought to a higher speed, say 1800 R. P. M., with continuedintroduction of the slurry to the spinning charge.

With a suitably slow rate of feeding the slurry, its liquid content canbe filtered off through the solids and filtering medium in the basket,but this requires objectionable expenses of time and power in processingeach complete charge, and care must be exercised to avoid theaccumulation of a body of liquid in the charge, unless this invention isused to avoid the instability likely to result.

With a much faster rate of feeding, which hitherto has not beencommercially practicable under the stated conditions, the charge liquidaccumulates as an annular inner layer of the rotating charge while thesolids build up at a fast rate, and surplus liquid overflows the rim 6aof the basket top, being thus discharged in a manner similar to thatcommonly employed in operations using a basket of the bowl or solid walltype. This manner of operation heretofore has been dangerous and henceimpracticable in that the basket is likely to start gyrating and strikethe surrounding casing, with danger of complete disruption of the fastspinning machine, under unequal weight distribution in the liquidcontent of the charge.

With the use of this invention, however, the instability of thecentrifugal operation performed in this manner is overcome simply byinserting the stabilizing blades to a small depth in the surface of therotating liquid. Their insertion to a depth of about inch is generallysatisfactory. Whenever a tendency toward'excessive gyration or vibrationis observed, therefore, the operator merely engages the stabilizingblades with the liquid surface of the charge, and smooth, stable machineoperation is immediately restored. Each operating cycle thus can becontinued with very fast feeding of the liquid charge material into thebasket spinning at a very high speed, until the basket is substantiallyfull of the separated solids. The charging then may be discontinued, andthe scoop element may be activated to remove any surplus liquid from theinner surface of the charge. Then the basket may be accelerated, ifdesired, to an even higher speed, say 2200 R. P. M., at which residualliquid adhering to the solid particles is filtered off electively byextreme centrifugal force so as to yield the calcium carbonate in arelatively dry form.

According to another example, this invention may be applied for theseparation of suspended solid particles from liquid, such as in theclarification of sugar juice, by use of a large centrifugal basket ofthe bowl type with or without horizontal partition rings in the basket.In case of a basket with rings, the stabilizing projections or bladesare preferably spaced so that at least one of them will enter the bodyof liquid in each annular channel of the spinning basket. Through suchan application of the invention it is possible to achieve thecentrifugal separation of very fine suspended solids from liquids on alarge scale in a safe and economical manner, and at an efficiency far inexcess of that heretofore attained, by reason of the much greater speedsof rotation and centrifugal forces that can be safely applied to theliquid basket charge.

The present invention serves not only to enable the safe and stableoperation of heavy-duty centrifugals with liquid charges at speeds andcentrifugal forces far higher than were safely attainable heretofore,but it also alleviates the need, heretofore envisioned, for exceedinglyrigid and expensive constructions or mountings of centrifugal machinesintended for operation with liquid charges at high speeds.

It will be understood that the new principles, methods or structuresherein disclosed or utilized in the illustrative embodiment may beemployed in various ways or forms without departing from the inventiondefined in the appended claims.

I claim:

1. In combination with a centrifugal machine whereof the basket inrotation holds a spinning annular charge having at least an inner layerof liquid, a stabilizer comprising a drag member held inside the baskethaving a group of relatively fixed, substantially fiat bafiie elementslying in planes transverse to and spaced apart in the direction of theaxis of the basket and presenting free edges movable to and from thesurface of said liquid while the basket is spinning at high speed.

2. In combination with a centrifugal machine whereof the basket inrotation holds a spinning annular charge having at least an inner layerof liquid, a stabilizer comprising a drag member held inside the baskethaving a group of blades lying in planes transverse to and presentingfree edges spaced in the direction of the axis of the basket and movableto dispose said free edges in and away from the surface of said liquidwhile the basket is spinning at high speed.

3. In combination with a centrifugal machine whereof the basket inrotation holds a spinning annular charge having at least an inner layerof liquid, a stabilizer comprising a drag member held inside the basketand movable to and from the surface of said liquid while the basket isspinning, said member having a base extending in the direction of theaxis of the basket and a plurality of spaced blades on said base lyingin planes transverse to said axis with edges facing said liquid surfaceso as to be insertable into said surface by movement of said member in adirection away from said axis.

4. In combination with a centrifugal machine whereof the basket inrotation holds a spinning annular charge having at least an inner layerof liquid, a stabilizer comprising a drag member held inside the basketand movable toward and from the surface of said liquid while the basketis spinning, said member having a base extending in the direction of theaxis of the basket and a plurality of spaced blades on the base lying inplanes transverse to said axis with substantially parallel edges facingsaid liquid surface, and manually operable mechanism connected with saidbase and extending to an operating position outside the machine formoving the stabilizer so as to insert said edges into the spinningliquid surface.

5. In combination with a centrifugal machine whereof the basket inrotation holds a spinning annular charge having at least an inner layerof liquid, and comprising a feed tube arranged to introduce liquidcharge material into one end portion of the basket, a stabilizercomprising a drag member held inside the basket having a plurality ofrelatively fixed blades lying in planes transverse to and spaced apartin the direction of the axis of the basket with free edges to face theinner surface of the spinning liquid, said member being movable in apath transverse to said axis so as to move said free edges to and fromthe inner surface of the spinning liquid, said blades having a slightinclination across the direction of rotation of said surface toward saidone end portion.

6. In combination with a centrifugal machine whereof the basket inrotation holds a spinning annular charge having at least an inner layerof liquid, a stabilizer comprising a drag member held inside the basketadjacent the surface of the charge while the basket is spinning, saidmember having a base extending in the direction of the axis of thebasket and a plurality of blades on said base lying transverse to saidaxis with substantially parallel edges to face said surface, a feed tubeextending into said basket for introducing liquid charge material, saidbase mounted on said feed tube, and means mounting said feed tube formovement to activate and inactivate the drag member.

7. In combination with a vertical centrifugal machine whereof the basketin rotation holds a spinning annular charge having at least an innerlayer of liquid, and comprising a stationary casing surrounding thebasket, a feed tube extending vertically into the basket to introduceliquid charge material near the basket bottom, said tube mounted infixed position for turning movement on a vertical axis, a stabilizermounted on said feed tube inside the basket comprising a plurality ofvertically spaced blades extending transversely to said axis, saidblades having free edges to face the spinning liquid, mechanismconnected with said tube and extending to an operating position outsidesaid easing for turning said tube to activate and inactivate thestabilizer, a scoop element inside the basket near the top thereofmovable to and from a position to remove I 8 the rotating basketadjacent to the inner surface of the charge and having a plurality ofsubstantially parallel relatively fixed blades spaced apart in thedirection of and lying in planes transverse to the axis of the basket.

9. A stabilizer for a centrifugal machine whereof the basket in rotationhas at least an inner layer of liquid in its charge, comprising a dragmember having a base to be held inside and extend in the direction ofthe axis of the basket over a major portion of the internal height ofthe basket, a plurality of spaced substantially parallel bladesextending transversely from said base in substantially horizontalplanes, said blades having edges disposed to enter fluid spinning with acharge in the basket and being inclined so as to lie at a slight angleto said axis.

References Cited in the file of this patent UNlTED STATES PATENTS662,214 Wood Nov. 20, 1900 994,631 Berrigan June 6, 1911 1,002,471Thelitz Sept. 5, 1911 1,202,936 White Oct. 31, 1916' 1,212,638 Herr Jan.16, 191/ 1,267,419 Kaita May 28, 1918 1,286,626 Herr Dec. 3, 19182,013,109 Reynolds Sept. 3, 1935' 2,056,890 Pecker Oct. 6, 19362,313,644 Hvid Mar. 9, 1943 2,370,999 Schutte Mar. 6, 1945 FOREIGNPATENTS 442,943 France Apr. 25, 1912

